Docstoc

Steering Centre Pin Retention Mod

Document Sample
Steering Centre Pin Retention Mod Powered By Docstoc
					                                                        Safety Bulletin
            Safety Documents available at http://hastingsdeering.cat.com


  This Safety Bulletin provides the reader with a safety awareness of
  Caterpillar Off-Highway Truck Steering Centre Pin Maintenance.
Location Type:             All Mines and Quarries

Event:                     The Steering Centre Pin Retaining Bolts contained in the centre
                           steering arm pin joint can become damaged. If these bolts fail, the
                           pin may drop out of the bore.

Model:                     Caterpillar Off-Highway Trucks (OHT) 784 to 797 models.

                        Recommended Management Action Plan
Hastings Deering’s experience is to implement and follow the information outlined in
the following comments and advise that the information detailed here and in the
attached appendix of this bulletin should be added to the Operation and Maintenance
Guide of the relevant model OHT.
Comments:
    • Replace and properly torque the bolts contained in the pin joint whenever ball
        studs are removed from the centre arm.
    • Inspect the Steering Centre Pin Retaining Bolts for loosening and or damage at
        1000 hour intervals. Check the torque of the bolts - refer to relevant model
        Service Manual for correct specification
        NOTE: Use minimum torque specification when checking to ensure bolts are
        tight.


Steering Centre Pin Retaining Bolts




     •    As a secondary means to ensure that the pin does not fall completely from the
          bore, a pin strap may be installed. The strap is installed just below the pin on
          the bottom of the steering box. It is bolted to two bosses.
Cliff Melvin
Group Technical Services Manager
Hastings Deering (Australia) Ltd

“This safety Bulletin is to inform you of the recommendations of the supplier in respect of issues dealt with in the
Safety Bulletin and should not be used as specific advice in respect of any particular events. Advice from a qualified
repairer should be sought in respect of any particular events and Hastings Deering (Australia) Ltd accepts no
responsibility for any loss or damage occasioned by a party using this general Safety Bulletin rather than obtaining
their own specific independent advice in respect of any events occasioning equipment failures”.

Bulletin No.                4                   Issue Date:         26/02/2004       Revision Date
 PPL No.                   111                 Revision No.              0            Total pages             11

                                                   Page 1 of 11
APPENDIX




  Page 2 of 11
            SUBJECT: Steering Pin Strap Installation

Models: 784 (8GB) 784B (5RK) 784C (2PZ) 785(8BG) 785B (6HK) 785C (1HW)
785C (APX) (789 (9ZC), 789B (7EK), 789C (2BW), 793 (3SJ), 793B (1HL), 793C
(4AR,4GZ, ATY)

The machine must be shutdown and parked as per the Caterpillar Operation and
Maintenance Guide.
All safety precautions must be adhered to as per the Caterpillar Operation and
Maintenance Guide and any other local requirements.

The following procedure is written to cover non-structural welding to the specified area
and only for the specified purpose of fitting the Steering Pin Strap modification.

Note: Proper Welding Procedure on Machines and Engines with Electronic Controls is
found in Service Magazine 3rd November 1997 attached to the end of this instruction.

Cleaning
Thoroughly clean the steering casting bracket of oil, grease, paint, and dirt in the area to
be welded.

Personal Protection:
The Welding Operator must be provided with and use all necessary personal protection
equipment.
Do not weld in a confined area and assure that total weld fume in the operators breathing
zone is within safe limits.

Recommend Electrodes
There are three possible welding processes:

FCAW
GMAW
SMAW

Select the process which best fits your particular environment.

FCAW with E71T-I (ANSI/AWS A5.20) welding electrode and the manufacturers
specified shielding gases).This electrode may be used in all positions. The weld deposited
by these electrodes will have the following minimum mechanical properties:

500 MPa (72 KSI) Tensile Strength
420 MPa (60 KSI) Yield Strength
22% elongation in 50 mm (2 inches)
27 J (20 ft lbs.) Notch Toughness at - 18 degrees C (0 F)

Use the direct current electrode positive (DC reverse polarity) polarity setting and remove
the slag after every pass.



                                       Page 3 of 11
GMAW This welding process must be used with an external shielding gas (argon and
carbon dioxide) therefore the environment must be controlled. If welding outside,
provisions must be made to prevent the shielding gas from being blow away from the
welding zone. The process needs to be set up for out of position, which means proper
electrode and parameter selection. The process must be used with an approved welding
electrode type AWS ER70S-3 (A5.18 specification). The composition of the shielding
gas must meet the electrode's manufacturing recommendation. The weld deposited by
these electrodes will have the following minimum mechanical properties:

500 MPa (72 KSI) Tensile Strength
420 MPa (60 KSI) Yield Strength
22% elongation in 50 mm (2 inches)
27 J (20 ft lbs.) Notch Toughness at - 18 degrees C (0 F)

Welding parameters will vary due to weld position and manufacturer of the welding electrode.
For 0.8 mm. (0.035 inch diameter) electrode typical welding parameters should be:

Wire Feed Speed         Voltage          Approximate Amperage
Minimum 225 IPM           18                     160
Optimum 250 IPM           20                     170
Maximum 275 IPM           22                     180

Use the direct current electrode positive (DC reverse polarity) polarity setting and clean
after every layer.

SMAW process may also be used with E7018 (ANSI/AWS A5.5) welding electrode. The weld
deposited by these electrodes will have the following minimum mechanical properties:

500 MPa (72 KSI) Tensile Strength
420 MPa (60 KSI) Yield Strength
22% elongation in 50 mm (2 inches)
27 J (20 ft lbs.) Notch Toughness at -29 degrees C (-20 F)

These are low hydrogen electrodes and must be stored in an electrode oven at 250
degrees F when not in use. The electrodes may only be reheated once. If the electrodes
get damp, scrap or recondition them to manufacturer’s specifications.

The following chart relates to the electrode diameter and approximates current settings
for welding:

Diameter                Amps
3 mm (0. 12 5           130
4 mm (0.156")           180
4.8 mm (0. 166          260

Use the direct current electrode positive (DC reverse polarity) polarity setting and
remove the slag after every pass.




                                          Page 4 of 11
When welding do not allow the part to exceed 500 degrees F in temperature. If the
temperature exceeds this, stop and let the part air cool. Use a temperature stick to
measure and monitor the part temperature.

Inspection

The weld should be visually inspected. The weld shall be free from cracks, porosity,
undercut, and incomplete fusion. All weld quality shall conform to AWSD 14.3 or
Caterpillar Specification IE99. Grind, blend, machine, and paint as needed.

Welding should only be performed by a Trade Qualified person with appropriate welding
qualifications.


Weld Process
Attach the welding ground cable directly to the frame, as close a possible to welding area.
Do not allow welding current to travel through the machine's bearings or hydraulic
cylinders. Protect all hydraulic cylinders, struts, hoses, and machined surfaces from
sparks or spatter produced by the welding, chipping, and/or grinding operations.

The area to be welded and the surrounding area must be at a minimum temperature of
(16Deg C) 60 Deg F before and during welding.

Grind the area where the bosses are to be mounted completely to a clean metal surface
free of all rust, dirt, oil and grease.
Weld the bosses to the bracket with a 3 mm fillet weld completely around each boss. Be
sure that complete fusion is achieved. Do not leave any nicks, undercut, spatter, or arc
strikes. Remove any slag and spatter and after completion, apply a coat of paint to the
area.




Retaining Strap Installation Process

As a secondary means to ensure that the pin does not fall completely from the
bore, a pin strap may be installed. The strap is installed just below the pin on the
bottom of the steering box. It is bolted to two bosses.

785 Plate Fabrication and Installation Instructions

Fabricate one 7U-3307 Plate from structural steel with a minimum yield strength
of 207 Mpa (30,000 PSI). See Illustration 2 and Table 2 for the dimensions.

See the Illustrations for the proper location of the bosses. Weld to the bosses to
the steering box with a 3 mm fillet weld.




                                       Page 5 of 11
Illustration 1. Typical 785 Rear View

Table 1.

                                        Parts Required
           Item                 Qty                 Part Number          Description
            1                    2              8G-1779           Boss
            2                    2              6H-1717           Bolt
            3                    2              5P-8245           Washer
            4                    1              7U-3307           Fabricated Plate




                                     Page 6 of 11
Illustration 2.



Table 2.

    Item                                  Dimension

      A           10 mm (0.4 inch)

      B           304.0 +/- 2.0 mm (11.97 +/- 0.08 inch)

      C           31.04 +/- 0.5 mm (1.24 +/- 0.02 inch)

      D           241.3 +/- 0.5 mm (9.50 +/- 0.02 inch)

      E           100.0 +/- 2.0 mm (3.94 +/- 0.08 inch)

      F           50 +/- 1.0 mm (1.97 +/- 0.04 inch)

                  22.5 mm (0.88 inch) diameter
      G
                  2 holes




                                     Page 7 of 11
Illustration 3. Typical 785 Bottom View

Table 3.

Item           Dimension

H              120.7 mm (4.75 inch)

J              62 mm (2.44 inch)




                                   Page 8 of 11
789/793 Installation Instructions

Chamfer the base of the bosses as required to sit flat on the bottom of the
steering box. Weld to the bosses to the steering box with a 3 mm fillet weld.




Illustration 4. Typical 789/793 Rear View

Table 4.

                                          Parts Required
           Item                 Qty                    Part Number           Description
            5                       2              8R-7783            Boss
            6                       2              8T-4139            Bolt
            7                       2              8T-4223            Washer
            8                       1              4D-4906            Plate




                                        Page 9 of 11
Illustration 5. Typical 789/793 Bottom View



Table 5.

    Item                                 Dimension

     K         54 mm (2.1 inch)

     L         38 mm (1.5 inch)

     M         149 mm (5.9 inch)




                                   Page 10 of 11
Service Magazine

Media Number - SEPD0389-00       Publication Date - 1997/11/03      Date Updated - 1997/11/03




Proper Welding Procedure On Machines And Engines
With Electronic Controls {1400}
SMCS - 1400

All Machines And Engines With Electronic Controls

Proper welding procedures are necessary to avoid damage to electronic controls. The
Following steps should be complied with when welding on any machine or engine with
electronic controls.

1. Turn off the engine and put the key start switch in the off position.

2. Disconnect the negative battery cable at the battery or if the machine or engine has a
battery disconnect switch, open the switch.

NOTE: This is the position for machine service or storage.

3. Connect the welder ground cable directly to the actual machine member to be welded.
Place this clamp as close as possible to the weld to reduce the possibility of welding
current damage to the drive train bearings, hydraulic components, and electrical
components like cab ground straps and other machine components.



                                         NOTICE
       Do NOT use electrical components (ECM's sensors) or electronic
       component ground points for grounding the welder.


4. Protect any harnesses from welding debris or spatter.

5. Use standard welding procedures to weld the materials together.

Correlated and Prepared by Joe Thorburn, Hastings Deering (Aust) Ltd Group Technical
OHT Technical Communicator

Date 31/10/2002 Updated 27/02/2004




                                       Page 11 of 11

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:15
posted:5/5/2010
language:English
pages:11
Description: Steering Centre Pin Retention Mod